1. Field of the Invention
The present invention relates to a vehicle having a system and a method of diagnosing a secondary air injection apparatus. More particularly, the present invention relates to a vehicle having a system and a method of diagnosing a secondary air injection apparatus that can diagnose fault of the secondary air injection (SAI) apparatus without mounting an additional flow meter for detecting the fault at lines.
2. Description of Related Art
Recently, various technologies for reducing exhaust have been researched so as to meet strict exhaust regulations and one of such the technologies is catalyst heating.
According to the catalyst heating, an idle rotation speed (idle RPM) is raised for activating a catalyst at initial starting if an engine is not started for more than a predetermined time. If the idle rotation speed is raised compared to an engine load, a temperature of an exhaust gas is raised and a temperature of the catalyst is also raised when a high-temperature exhaust gas flows through the catalyst. Therefore, activation of the catalyst may be quickly achieved and the exhaust may be reduced.
Secondary air injection (SAI) technology has been researched for the catalyst heating. According to the SAI technology, a portion of intake air is supplied to an exhaust manifold or an exhaust line so as to burn the exhaust gas exhausted from a combustion chamber again. If the exhaust gas is burnt again, a temperature of the exhaust gas rises and accordingly the temperature of the catalyst also rise.
An SAI apparatus will be described in further detail.
The SAI apparatus includes an intake line for supplying air to the engine, an exhaust line for exhausting the exhaust gas generated at the engine, and an SAI line for connecting the intake line with the exhaust line.
An air filter is mounted at the intake line and a catalytic converter is mounted at the exhaust line. One end of the SAI line is connected to the intake line located at a rear end of the air filter, and the other end of the SAI line is connected to the exhaust line located at a front end of the catalytic converter. In addition, an SAI valve is mounted at the SAI line so as to selectively supply the air in the intake line to the exhaust line. That is, the air in the intake line is supplied to the exhaust line through the SAI line such that the exhaust gas in the exhaust line is burnt again if the SAI valve is open.
In addition, an SAI pump is mounted at the SAI line. In order to supply the air to the exhaust line through the SAI line, a pressure of the SAI line is to be higher than that of the exhaust gas. Therefore, the SAI pump raises the pressure of the SAI line so as to supply the air to the exhaust line efficiently.
Meanwhile, a flow meter is to be mounted at the SAI line and detects a flow amount of the SAI so as to meet reliability and on-board diagnosis (OBD) regulations of the SAI apparatus. That is, fault such as stuck of the SAI valve can be diagnosed by detecting the flow amount of the SAI flowing into the SAI line.
If the flow meter is mounted at the SAI line, however, cost may increase and it may be difficult to design layout of the SAI line.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.